Field of the Invention
The invention relates to a method for producing a semiconductor modular structure with a metal base plate, a ceramic substrate being joined materially to the base plate and being provided with a metallizing, and semiconductor bodies being materially joined to the metallizing, in which the base plate is convexly deformed by a pressure ram.
Such a method has been described, for instance, in German Published, Non-Prosecuted Application DE 39 40 933 A1. There an already-soldered modular structure is placed by its base plate on a compression mold that is concave with respect to the base plate. Then the mold is heated to just below the melting temperature of the solder, and the metal base plate is deformed by a pressure ram having a shape which is adapted to the compression mold. The pressure ram is placed on the long sides of the base plate. The deformation of the base plate compensates for the bimetallic effect that results from the material joining of the ceramic substrate and the base plate. The mechanical strain between the substrate and the base plate is reduced by plastic deformation in the layer of solder. The compensation results in the base plate being shaped convexly with respect to a cooling body and being able to be placed flat against the cooling body by means of screws.